small leak in pipe under screed?

s7ryf3925pivug

The central heating system is losing pressure gradually.

A new boiler was installed in a different location and some new pipework. Don't see any leak in the new pipework.

My kid is about 11kg and took to standing on the valve of one of the rads for a while. We also got a big new fridge and I'm wondering if the exposed pipe behind it might have taken a knock when it was delivered. Don't know if either of those things could damage the pipe beneath?

The central heating is losing pressure gradually over several days. The plumber who installed the new boiler seemed unconcerned, said it was about a cupful that would have leaked out, and said he would put in leak sealer. (There are 8 rads in a bungalow that's about 90 sq m so.) Showed how to repressurize the system. Either I'm doing it wrong or it takes far too long to indicate a cupful. It is still happening since the leak sealer was added.

The first time I noticed it a rad was pretty noisy. I bled it and lots of air came out. The pressure of the system was zero after bleeding it. It had dropped a bit before I bled it.

Mainly I'm concerned that this will lead to bigger problems if it's not addressed, such as rising damp or other structural issues? No idea how to go about locating the leak? Googling shows horror stories with excessive collateral damage when people do.

Most of the pipework is actually above the floor. I think only two rooms have them in the screed. One of those has a new floor with damp proof membrane on top of the screed. The other is tiled, and we're planning to tile over it.

Would it make sense to get the piping under the screed bypassed with new accessible pipes? Skip digging them up altogether? I saw something about boxing the pipes in plywood channels in the screed alternatively..?

Should I hold off repressurising the system until this is fixed as I'm essentially pouring water into my subflooring? Or is it safe enough to ignore it because it is in fact a small volume?

Any other thoughts?

John.G

It does look likely a leak but what you can check easily yourself if you have a external expansion vessel. remove the plastic cap at the end and you will see a schrader valve (like on your car tyre), press the inside "pin" on this with your nail and see if air or water comes out or maybe no pressure present.

jimf

the problem with constantly topping up the system is you are adding fresh water all the time


over time this will cause problems with your new boiler and rads it needs permanent addressing asap

John.G

The reason I suggested checking the E.vessel is that if its full of water or has lost its pre pressure then as the air is being expelled from the system there is no reserve to take its place, of course eventually then the PRV would start lifting.

s7ryf3925pivug

I see that what I thought was the expansion vessel was disconnected when the new system was put in. There is just a tank above the boiler that is used as a reservoir for a domestic pump to improve shower pressure. It's a combi system. Do some systems not use expansion vessels?

John.G

Leon Thoughtless Kindle wrote: »

I see that what I thought was the expansion vessel was disconnected when the new system was put in. There is just a tank above the boiler that is used as a reservoir for a domestic pump to improve shower pressure. It's a combi system. Do some systems not use expansion vessels?

I assume you have a combi gas boiler?, if so, then the expansion vessel is integral inside the boiler casing and you can't access it, some oil combis also have a integral expansion vessel.

s7ryf3925pivug

Tile has cracked and loosened slightly in kitchen for unknown reasons. Is this likely to be related..?